Wood Turtle-Human Interaction and Policy

Comp Sci 699Fall 2012

Is it possible to have sustainable population of Wood Turtles while also having a sustainable

(continuous) growth rate for the human population in Vilas County, WI?

Time Scale◦ Refined down to hours.

Ticks= Hours◦ Days, months, years tracked

Model Methodology

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Turtle Behavior◦ Daily life: eat, bask, sleep in proper◦ Mating during proper periods: turtles are male or

female, during mating periods females have a chance of being “fertilized” if male turtles nearby

◦ For every “fertilized” female new turtles are spawned into world during proper months; number of turtles based on survival rates past first 5 years (we only model turtles that would survive into adulthood, since there is such a high mortality rate in the first 5 years)

Model Methodology

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Turtle Behavior (cont'd)◦ Hibernation during winter◦ Natural lifespan: ~40 years◦ Can mate if over 15 years old (sexual maturity)

Original population in world starts at age 15 so mating can be observed immediately

◦Day-to-day survival chance high if not in contact with human development

Model Methodology

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Human Behavior◦ Humans move in beginning of each year◦ If unaffected by policy, prioritize their settlement in

following order: Near other humans AND lakes Near lakes Near humans Any suitable land cover (not marsh, water, etc.)

Model Methodology

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Default◦ Last place food was found is remembered◦ Return to these locations when hungry◦ No more food at location initiates new search

Left Leaning walk◦ Likely the most realistic memory model

Turtle Memory

Food Zones◦ Similar to Default◦ Multiple food locations remembered◦ Exhausts memory bank before initiating new

search

Avoid Humans- ◦ Turtles crossing developed patches get confused

Intended location lost, random heading◦ If turtle survives, will remember developed patch as “bad”

Will avoid “bad” patches in the future

Turtle Memory

Passing through developed patch increases chance of turtle death

Developed patches can no longer be food sources Using Avoid Humans memory model

◦ Possibility for light confusion◦ Navigating around developed patches challenging with high

Human densities

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Wood Turtle-Human Interaction

No Build◦ Our experimental control for the turtle population◦ No new incoming humans

Free Build◦ Humans can build anywhere, based on what is

most desirable Most desirable: Near other humans AND Near water

(lakefront) Close to water > Close to humans

Policies

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600m Buffer◦ No new development can occur within 600m of a

lakefront◦ Keeps entirety of Wood Turtle range free of

development 300m Buffer

◦ No new development can occur within 300m of a lakefront

◦ Keeps “inner” 300m free from development

Policies

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Spaced Housing◦ No new buildings within 180m of each other◦ Promotes urban sprawl◦ Ideally keeps corridors open for Wood Turtle

movement Grouped Housing

◦ New buildings can only be constructed next to a newly arrived human

◦ Limits urban sprawl

Policies

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Ran simulation with No Build to analyze Wood Turtle behavior◦ Runs varied

Initial spawn of turtle population random. Problems occurred when near human development

Mating population of turtles can not successfully reproduce near humans

◦ Final mean population decreased slightly after 40 year

Experimental Control

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Is it possible to have sustainable population of Wood Turtles while also having a sustainable

(continuous) growth rate for the human population in Vilas County, WI?

Modeled “Current” conditions◦ Free Build Policy◦ Default Memory

Turtle Population reaches 0 after 71 years◦ Can not complete lifecycle

No basking No nesting sites No food Poor water quality

Without change to building policy, there can not be a sustainable populations of Wood Turtles while the influx of humans remains constant

Our Answer

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600m Buffer◦ Turtle populations after 40 years remain

comparable to control Slight population increase Most Wood Turtle activity takes place within 600m of

water Little human encroachment allows greater stability to

the turtle population◦ May not be feasible to implement

Socially unacceptable Push back from public

Turtle Friendly Policy

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300m Buffer

Middle Ground?

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Default Food Zones Avoid Humans0

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300m Buffer Policy

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Grouped Housing

Middle Ground

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Default Food Zones Avoid Humans0

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Grouped Housing PolicyFi

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Spaced Housing◦ Encourages urban sprawl◦ More humans and roads

Bad conditions for turtles◦ Success for this policy could increase with better

understanding of turtle memory

Least Effective Policy

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Default Food Zones Avoid Humans0

102030405060708090

100

Spaced Housing Policy

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Future Additions◦ Integration with GIS◦ Obtain better data using radio telemetry

Map turtle locations over time Window into actual turtle memory

Simulating Economy/ Human Satisfaction◦ Compare versus Turtle population

Policy is a tradeoff between the human and turtle factor but we are only really looking at turtles

Run the model more realistic turtle population for long periods of time

Future Extensions

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Questions?

Add ppt slide with more extensions◦ Protected lakes/ areas◦ Differential survival for males and females

Females roam farther, subject to higher mortality chance

◦ Point out research needs

To Do

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